Electric safety-fuse.



W. 0. SNELLING. ELECTRIC SAFETY FUSE. APPLICATION FILED MAR. 22; 1915. RENEWED JUNE a. 1918.

1,288,724. Patented Dec. 24, 1918.

INVENTOR WW I E I Wa/fer 0. Jae/0'09 ZZQM E MELMXQWQW ATTORN EY WALTER O. SNELLING, 0F PITTSBURGH, PENNSYLVANIA.

ELECTRIC SAFETY-FUSE.

Specification of Letters Patent.

Patented Dec. 24, 1918.

Application filed March 22, 1915, Serial No. 16,003. Renewed June 8, 1918. lfierialNo. 239,041.

T 0 all whom it may concern:

Be it known that I, WALTER O. SNELLING, a citizen of the United States, and a resident of Pittsburgh, in the county of Allegheny and'State of Pennsylvania, have invented a new and useful Improvement in Electric Safety-F uses, of which the following is a specification. v

My invention relates to electric circuit interrupters of the fuse type, which embody a fusible element adapted to melt and to thereby interrupt the circuit when the current therein reaches a predetermined value, and it has special reference to safety fuses, in which the fusible element is associated with means for preventing-destructivearcing at the instant when the fusible element melts or blows.

The object of my invention is to provide a circuit interrupter of the safety, fuse type which shall embody means for surrounding the fuse, at the instant of fusion, with an inert atmosphere in which combustion cannot occur, whereby the ignition of inflammable objects in the vicinity of the fuse is entirely prevented.-

More particularly, the object of my invention is to provide afusible element for safety fuses that shall have associated with it a solid or semi-solid body which is'vaporizable at the heat of fusion of the fusible element and-which, when vaporized, produces an atmosphere that will neither burn nor support combustion. This mass of Va por performs the double function of absorbing and rendering latent a large portion of the heat produced by the blowing fuse, and of forming an atmosphere in which combustion cannot occur. As sources of such fire-preventing vapors, certain solid and semi-solid halogenated carbon compounds are well suited.

Various embodiments of my invention are illustrated in the accompanying drawing, in which Figure 1 is'a side view, partly in elevation and partly in section, of 'a cartridge fuse constructed in accordance with my invention; ,Fig. 2 is a longitudinal sectional view of' a modified form of cartridge fuse; Fig.3 is a side view, partly in elevation and partly in section, showing a fuse wire provided with a coating of vapori'zable fire-preventing material; Fig. 4 is a plan view of a fuse strip or tape carrying spaced bodies of fire-preventing material Fig. 5

is a side view, partly in elevation and partly in section, showing a modified form of cartridge fuse; Fig. 6 is a longitudinal sectional view of another form of fuse, and Fig. 7 is a side elevational view, partly in section, showing a modified method of applying my invention to a fuse wire.

The blowing of electric fuses is an ever-present source of fire danger, especially in high voltage circuits and where the fuses are placed near inflammable material. The arcing of fuses may also cause inconvenience and damage when, as is'frequently the case, a large number of fuses are mounted upona single fuse board, where one fuse, when it blows, will sometimes strike an are .that is' violent enough to set oif a whole Such a Wholesale series of" other fuses. blowing of fuses will often disable a whole distribution system.

For the purpose of avoiding the fore-. going inconveniences and dangers, many safety fuses have been designed'in whichthe fusible element is surrounded by a mass of finely divided refractory material, such 'as asbestos, magnesia, sillca, talc, llmestone and the like. In other safety fuses, the fusible elementis immersed in a'body of liquid such as carbon tetrachlorid or a hydrocar bon oil of high flashing point, which is intended to quench the arc, and stillother fuses arefilled with metallic salts, such as the alkali metal carbonates, which are supposed to diminish arcing. All of these arerestraining substances are effective to, a limited degree only, since the solid materials heretofore used will not prevent arcs from forming, and will not afford protection if thefuse container is ruptured by the are, as frequently happens. Liquid arc-restraining mediums are somewhat more effective,

but they easily escape from their containers,

and-therefore require specially constructed and often complicated receptacles. Carbon tetrachlorid, on account of its solvent ac-' tion upon many organic substances, requires particularly careful selection and construction of containers.

, According'to my present invention, I effectively prevent destructive arcing of fuses by the-use of solid or semi-solid fire-preventing substances, which may be readily and inexpensively applied to existing forms of fuses, both open and inclosed, and which require no special receptacles. A large num- .l 2. i I; v I I i I N fire preventing agents, but at present, I prefer to make use of certain halogenated. carbon I -polysubstitution products of ethane, prober of substances are suitable for use as the comppunds particularly chlorin pane, naphthalene and other hydrocarbons,

v to the use of these specific substances, or of I my invention are this class of substances, since any material having the requisite properties, ture of such materials, may be v; employed within the-scope of my invention.

Some bf the numerous applications of illustrated in the accompanying drawing. Fig. lshows an ordinary inclosed or cartridge fuse adapted for hightension service and consisting of a. tubular casing 1, which may be of paper, "fiber or other suitable non-conducting material, provided with metallic caps or ferrules 2, to

which terminals 3 are welded. or otherwise attached. "A'qwire or .strip 4, of a fusible metal or alloy, is inclosed within the casing 1 and is electrically connected, by soldering or otherwise,

to both-of the ferrules 2. .The space between. the wire 4 and. the walls of the casing 1 is partly or entirely'filled with one of the arc-preventing substances enumerated above, for example, ethane hexachlorid, which is a pulverulent body that may readily be poured into the casing.

In Fig. 2, a modified form of cartridge fuse is shown, in which the fusible metal is formed into a tube 7, inclosing a mass 8 of ethane hexachlorid or other suitable substance. The ends of the tube are pressed together and bent over, forming contact terminal members 9. Y

Fig. 3 shows an ordinary fuse wire 10 rovided with a coating 11 of ethane hexa-. chlorid or the like, This simple form of fuse is perfectly safe,- even in the vicinity of inflammable bodies such as draperies and the like, because of thepositive and very rapid fire-preventing action of the halogenated substances mentioned above. It may therefore be frequently substituted for'cartridge fuses, at a considerable saving in expense.

A modification of the fuse shown in Fig.

3 is illustrated in Fig. 4, which shows a or any mixflat strip or ribbon 12v of fusible metal, provided at intervals with perforations 13' which are filled with the fire-preventing material. Since the cross-sectional area of the strip is decreased at these perforations, and the resistance correspondingly increased, the fuse will invariably blow at one or more of these points, and the meltin of the metal will be accompanied by the V0 atilization of the fire-preventing substance. 7 The perforations 13 may extend either partly or. completely through the strip 12..

Fig. 5 shows a cartridge fuse in which the structures shown in Figs. 1 and 3 are combined. The fuse consists of an insulating tubular casing 14, ferrules 15 and terminals 16 similar to those shown in Fig. 1, together with a fuse wire 17 which, like the wire shown in Fig. 3, is provided with itkcoating 18 of ethane hexachlorid or the '1 e.

Another modified form of fuse is illustrated in Fig. 6, which shows a tube 19 of fusible metal, into the ends of which terminal contact members 20 are inserted and firmly secured. The ends of the terminal members 20 may be bent into hooks 21, as shown, for convenient. attachment to binding posts, and the sp-ace' 22 between the ends of the terminal members 20, within the tube 19, is partly or wholly filled with ethane hexachlorid or other fire-preventing substance of the kind described above. When current passes from one of the terminals 20 to the other, it traverses the relatively thin wall of the tube 19. between the ends of the terminals, and, in case of overload, the fuse.

will melt'at this point and will vaporize the chlorinated hydrocarbon. I

A further modification of my invention, as applied to a fuse wire, is shown in Fig. 7.

"'A-wire 23, of fusible metal, is reduced in cross-sectional area at one or more places 24:, and ethane hexachlorid, or other suitable material, is applied at these reduced portions of the wire, in such quantity that the total diameter at these points is substantially the same as that of the remainder of the wire, Fusion ofthe wire will, of course, occur first at the reduced portions, and the adjacent fire-preventing material will be vaporized. Y

Many other structural embodiments of my invention may obviously be devised, and it is therefore to be understood that the structures which I have shown and described are merelyillustrative, It is also to be understood that my invention comprehends the use of all solid and semi-solid non-explosive substances that can be volatilized into a firepreventing vapor, and that no limitations are to be imposed upon my invention except 1. A safety fuse for electric circuit control comprising a body of readily fusible conducting material in contact With a nonliquid, non-explosive, vaporizable fire-preventing material. 7 r

2. A safety fuse for electric circuit control comprising a body of readily fusible conducting materialassociated With a non-fluid,

non-explosive, halogenated carbon compound that is volatilizable into a fire-preventing 3. A safety fuse for electric circuit control comprising a body of readily fusible conducting material associated with a non-fluid chlorinated carbon compound that is volatilizable into a fire-preventing vapor.

4. A safety fuse forelectric circuit control comprising a body of readily fusible conducting material associated with an-ethane polyhalid.

5. A safety fuse for electric circuit control comprising a body of readily fusible conducting material associated with ethane hexachlorid.

jacent toand in Contact With, the said body of fusible material.

8. safety fuse for electric circuit control comprlsing a casing, a body of fusible conducting material disposed therein, and

a body of non-liquid, non-explosive and wholly vaporizable fire-preventing material at least partly surrounding the said body of conducting material.

9. A safety fuse for electric circuit control comprising a body of fusible conducting material having at least one portion of'reduced cross-sectional area, and a body of non-explosive and-Wholly'vaporizable firepreventing material disposed adjacent to the reduced portion of the said fusible material.

10. A safety fuse for electric circuit control comprising a body of fusible conducting I material carrying. a body of solid or semisolid vaporizable and non-explosive firepreventing material; v

11. A safety fuse fol-electric circuit control comprising a body of fusible conducting material carrying a body of solid or semisolid halogenated carbon compound that is volatilizable into a fire-preventing vapor.

In testimony whereof, I have hereunto subscribed my name this 19th day of March,

WALTER O. SNELLING. Witnesses:

D 1. BROWN, M. R. MOKEOWN. 

